全部书籍

专业

应用 关于 Coach 登录 开始阅读

书籍暂未推出简体中文版——当前显示英文版。

Mathematics · 术语表

什么是 Radian?

Definition 14.1 High School Mathematics · 第 14 章 — Trigonometry: The Unit Circle

Let C\mathcal C be the circle of radius 11 centered at the origin OO, and I(1,0)I(1, 0). The radian measure of an angle at the center of C\mathcal C is the length of the arc it cuts on C\mathcal C. Since the full circle has circumference 2π2\pi:

360∘=2π rad,180∘=π rad,1 rad=180∘π≈57.3∘.360^\circ = 2\pi \text{ rad}, \qquad 180^\circ = \pi \text{ rad}, \qquad 1 \text{ rad} = \frac{180^\circ}{\pi} \approx 57.3^\circ .
在原文中阅读 →